rcu: Remove Classic RCU

Remove Classic RCU, given that the combination of Tree RCU and
the proposed Bloatwatch RCU do everything that Classic RCU can
with fewer bugs.

Tree RCU has been default in x86 builds for almost six months,
and seems to be quite reliable, so there does not seem to be
much justification for keeping the Classic RCU code and config
complexity around anymore.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: akpm@linux-foundation.org
Cc: niv@us.ibm.com
Cc: dvhltc@us.ibm.com
Cc: dipankar@in.ibm.com
Cc: dhowells@redhat.com
Cc: lethal@linux-sh.org
Cc: kernel@wantstofly.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 10 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 1ce05a4cb5f6..d10f31dfa0b2 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -316,21 +316,13 @@ choice
         prompt "RCU Implementation"
         default TREE_RCU
 
-config CLASSIC_RCU
-        bool "Classic RCU"
-        help
-          This option selects the classic RCU implementation that is
-          designed for best read-side performance on non-realtime
-          systems.
-
-          Select this option if you are unsure.
-
 config TREE_RCU
         bool "Tree-based hierarchical RCU"
         help
           This option selects the RCU implementation that is
           designed for very large SMP system with hundreds or
-          thousands of CPUs.
+          thousands of CPUs.  It also scales down nicely to
+          smaller systems.
 
 config PREEMPT_RCU
         bool "Preemptible RCU"